One example of a lubrication system for use with an internal-combustion engine is disclosed in U.S. Pat. No. 5,588,405 issued to Atsushi Sawa. The engine includes a gearbox incorporated into the crankcase. Oil ducts deliver lubricating oil to the camshaft and to the gears within the gearbox. The oil is circulated within the engine between the crankshaft, various oil-consuming devices, and an oil sump by an oil pump.
Additional lubrication is required in engines that have manual gearboxes. In particular, in manual gearboxes the gears are moved or shifted by gearshift sleeves and gearshift forks. The gearshift sleeves are moved axially along one or more shafts by one or more gearshift forks. Friction between the gearshift sleeves, the gearshift forks, and the shafts can cause premature wear in the gearbox. It is therefore desirable not only to supply lubricating oil to the gears and to the shafts within the gearboxes but also to supply lubricating oil to the gearshift sleeves and to the gearshift forks.